Please my nephew has locked his iPad, there's a padlock with an arrow round it.
Double-click the Home button and repeatedly swipe right until you get to the Portrait Orientation Button all the way on the left. Tap it.
It means that the rotation is locked.
Under the volume rocker switch is a little switch that can be an 'all mute' or 'rotation lock', so you can look into that.
You can learn more about that:
The User Guide is available at http://support.apple.com/manuals/ or downloadable from iTunes as an iBook.
I tried what you said as that is the symbol , but it's still not unlocking, does it matter that it's an iPad 1 at all?
Here you go: iPad: Understanding the side switch
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